Static convergence device for electron beams

ABSTRACT

A static convergence device for a plurality of coplanar electron beams in a color television picture tube comprises a plurality of magnet holding members disposed around the neck region of the picture tube, each member adapted to be rotated around the neck of the picture tube and including a plurality of magnetic poles for producing a magnetic field within the neck region. The magnetic poles are disposed on respective rings for producing 1) opposite direction motion of substantially only the outer beams, 2) the same direction motion of substantially only the outer beams, and 3) the same direction motion of all of the coplanar beams.

United States Patent [191 Thompson et al.

[ Apr. 30, 1974 STATIC CONVERGENCE DEVICE FOR ELECTRON BEAMS Inventors: Ira Foy Thompson; Joseph Leland Smith, both of Indianapolis, Ind.

Assignee: RCA Corporation, New York, NY.

Filed: Feb. 26, 1973 Appl. No.: 335,452

US. Cl 335/212, 313/77 Int. Cl. H011 7/00 Field of Search 335/210, 212, 213; 313/77 References Cited UNITED STATES PATENTS Mirsch 335/212 Primary Examiner-George Harris Attorney, Agent, or Firm-Eugene M. Whitacre; Paul J. Rasmussen 1 71 ABSTRACT A static convergence device for a plurality of coplanar electron beams in a color television picture tube comprises a plurality of magnet holding members disposed around the neck region of the picture tube, each member adapted to be rotated around the neck of the picture tube and including a plurality of magnetic poles for producing a magnetic field within the neck region. The magnetic poles'are disposed on respective rings for producing l) opposite direction motion of substantially only the outer beams, 2) the same direction motion of substantially only the outer beams, and 3) the same direction motion of all of the coplanar beams.

12 Claims, 16 Drawing Figures PATENTEBRFR 30 I974 SHkET 1 [If 3 24a 24b 25a 25b 26 j BACKGROUND OF THE INVENTION This invention relates to a static convergence assembly for converging a plurality of in-line electron beams of a color television picture tube to a common area on the viewing screen.

It is common practice to use magnetic structures associated with the electron beams of a color television picture tube to converge the beams at the center of the picture tube viewing screen. Such an adjustment is known as static convergence. Usually associated with the magnet structure which is located outside of and around the neck region of the picture tube are internal pole pieces associated with respective ones of the beams. One problem associated with structure of this type is that the internal pole pieces create interference with the deflection yoke field, the deflection yoke usually being placed a short axial distance along the neck region of the picture tube from the location of the pole pieces. Similarly, the magnetic yoke field interferes with the convergence pole pieces with the result that proper convergence of the beams independent of the magnetic beam deflection field is difficult to achieve.

A magnetic beam adjusting apparatus for use with an in-line color television'picture tube without internal pole pieces is disclosed in co-pending application Ser. No. 217,757 filed Jan. 14, 1972, U.S. Pat. No. 3,725,831 on Apr. 3, 1973 for Robert L. Barbin and entitled, Magnetic Beam Adjusting Arrangements. In that application is described a static convergence as sembly including a magnet holding member which in one embodiment is shaped like a ring encircling the neck of the picture tube and having four magnetic poles spaced at 90 intervals around the circumference of the ring and alternating in polarity for producing a quadripolar magnetic field for moving the two outside or off center beams in opposite directions. In conjunction with this first ring member is a second ring member including six magnetic poles disposed at 60 intervals around the circumference of the neck region, the six magnetic poles alternating in polarity for producing a sextipolar magnetic field for moving the two outside beams in the same direction. Both of the above described magnetic ring structures have substantially no effect on the center one of the three in-line beams. The described ring magnet structures may advantageously be used in combination with two purity rings, each magnetized across a diameter of a ring for effecting movement of all three beams in the same direction, for accomplishing both purity and convergence adjustments.

In accordance with one embodiment of the invention, a beam adjustment assembly for converging a plumagnet holding member encircling the neck region for producing magnetic fields in the same direction on diametrically opposite sides of the magnet holding member for effecting movement of the two outside beams in the same direction.

In another embodiment of the invention the first means includes a magnet holding member containing three magnets mounted at intervals around the circumference of the member and having like poles pointed inwardly toward the neck region. The second means includes a member having a plurality of magnetic pole regions adjacent the inner circumference of the member for producing negative fields in opposite directions at diametrically opposite sides of the member for effecting movement of the two outside beams in opposite directions.

In another embodiment of the invention, each of the above means includes two similar magnet holding members, the polarity of the magnets of one member being opposite to the polarity of the magnets of the other member.

In another embodiment of the invention, only one magnet holding member each of the type described above is utilized but the members are adapted to allow radial movement of each of the magnets for effecting control of the amount of magnetic flux within the neck region.

A more detailed description of the invention will be given in the following specification and accompanying drawings, in which:

FIG. 1 is a diagrammatic top view of one embodiment of a static convergence assembly according to the invention mounted on an in-line beam color television picture tube;

FIG. 2 is a disassembly side view of the static convergence assembly illustrated in FIG. 1;

FIG..3 is an end view looking from the right side of the static convergence assembly illustrated inFIG'. 2;

FIGS. 4 and 5 illustrate the location of the magnetic poles of individual magnet holding members of the static convergence assembly of FIG. 2; I

FIGS. 6a, 6b and 6c illustrate the effect of the static convergence assembly for moving electron beams in opposite directions;

FIGS. 7a, 7b and 7c illustrate the effect of the static convergence assembly for moving the electron beams in the same direction;

FIGS. 8a, 8b and 8c illustrate the effect of a purity ring assembly utilized with the static convergence assembly for moving all three of the electron beams in the same direction;

FIG. 9 illustrates a magnet holding member of the static convergence assembly in accordance with another embodiment of the-invention; and

FIG. 10 is a cross sectional view of the magnet holding member of FIG. 9.

DESCRIPTION OF THE INVENTION FIG. 1 is a diagrammatic top view of one embodiment of a static convergence assembly according to the invention mounted on an in-line beam color television picture tube. A color television picture tube comprises a glass envelope 11 having a front faceplate or viewing screen 12. On the inside of envelope 11 mounted closely adjacent the faceplate 12 is a shadow mask 13 forming a plurality of apertures 13a through which electron beams pass to excite different color phosphor elements deposited on the inside of faceplate 12. Around the neck portion of the picture tube at the end remote from the faceplate is mounted a deflection yoke 14 which serves to deflect the electron beams horizontally and vertically to form a scanned raster on the viewing screen.

Mounted behind the deflection yoke around the neck portion of the glass envelope is a static convergence assembly 16 which will be described subsequently. Included within the envelope 11 of the picture tube is the neck portion is an in-line electron beam gun assembly, not shown, for producing separate blue, red and green beams which are directed toward the faceplate 12. The purpose of the static convergence assembly 16 is to converge the three blue, red and green beams to a common area at the center of the viewing screen. The static convergence assembly 16 is necessary because due to manufacturing variations within the electron beam gun assembly and in the placing of the electron guns within the picture tube, it normally occurs that the three beams will not converge on the same area at the center of the screen. Thus, it is the purpose of the static convergence assembly 16 to provide suitable magnetic fields for converging all three of the electron beams a the center of the viewing screen.

FIG. 2 is a detailed disassembly side view of the static convergence assembly illustrated in FIG. 1. The central portion of assembly 16 comprises a hollow, cylindrical member 17 designed to slip over the neck portion of the glass envelope of the picture tube. The front portion of the cylinder 17 is threaded to receive a locking collar which is used to lock the various convergence members in place once they are adjusted. A collar portion 18 at the rear of cylinder 17 provides a shoulder against which the various convergence members are placed. The rear of cylinder 17 comprises a plurality of fingers 19 which are secured by means of a metal clamp 21 to the neck of the picture tube to prevent movement of cylinder 17 relative to the picture tube. As seen in FIG. 1, the static convergence assembly 16 .is secured to the neck of the picture tube to the rear of the deflection yoke 14 and generally over the region of the neck which contains the electron beam gun assembly.

At this point reference is made to FIG. 3 which is an end view looking from the right hand side of the static convergence assembly 16 of FIG. 2.

The convergence members of static convergence assembly 16 of FIG. 2 will be described in the order in which they are mounted around the cylinder 17. The first components are a pair of purity rings 22a and 22b, each having at least one protruding tab portion 22c to facilitate rotational movement thereof, separated by a paper ring 231;. Paper ring 23a facilitates individual movement of the two purity rings. A second paper ring 23h spaces a pair of magnet holding ring members 24a and 24b from the pruirty rings. This paper ring 23!) prevents motion of the other components when magnet rings 24a and 24b are rotated. Each of magnet rings 24a and 24b preferably has one or more protruding tabs 24c to facilitate rotation of the individual rings. A third paper ring 230 separates a second set of magnet holding ring members 25a and 25b from the set of magnet rings 24a and 24b. Each of rings 25a and 25b preferably has at least one protruding tab 25c to facilitate rotational movement. A fourth paper ring 23d spaces the second set of rings 25a and 25b from a locking collar 26 which is threaded to mate with the threads 20 of cylinder 17 to lock all of the rings in place once they are adjusted. Locking rings 26 also preferably has at least one protruding tab 260 to facilitate rotating the ring'26 in relation to cylinder 17. Preferably all of the components of the static convergence assembly 16 with the exception of metal clamp 21, metal purity rings 22a and 22b, the individual magnets of each of the ring members 24a and b and 25a and b, and paper ring washers 23a-d are made of a non-magnetic material such as plastic. This is desirable in that it minimizes undesirable interaction between the fields of the convergence ring members and the deflection yoke. The purity rings are metal, however, because they are located far enough from the deflection yoke so that the interaction is not objectionable. The magnets discussed above, and shown in more detail in FIGS. 4 and 5, may be either of a permeable or a nonpermeable magnetic material; however, a nonpermeable material magnet is preferred because it will not interfere with any electromagnetic field, such as the deflection yoke field, in the area near the rings.

Purity ring members 22a and 22b are preferably metal rings magnetized across their diameters to form two opposite polarity magnetic poles diametrically opposed from. each other on each ring. Ring member 24a has three recesses formed on one side thereof to contain three permanent magnets placed therein such that the three south magnetic poles ofthe. magnets are disposed closest to the picture tube neck receiving aperture at intervals about the ring. Magnet ring member 24b is similar to ring 24a except it has three permanent magnets placed thereon at 120 intervals and having their north magnetic poles closest to the picture tube neck receiving aperture. Magnet ring member 25a preferably has two permanent magnets disposed diametrically within recesses on one surface of the ring such that the magnetic south poles are closest to the neck receiving forming two south magnetic poles in that region. Magnet ring member 25b is similar to magnet ring 25a except that its two permanent magnets placed therein have their north poles closest to the neck receiving aperture for forming two north magnetic poles diametrically opposite each other in that region.

FIGS. 4 and 5, respectively, illustrate the location of the magnetic poles of individual ring members 25b and 24a of the static convergence assembly of FIG. 2. In FIG. 4 ring member'25b has disposed on it two diametrically opposite permanent magnets 27, each magnet having its north pole closest to theportion of ring member 25b which encircles the neck portion of the picture tube. Magnetic flux paths for each of the magnets are indicated by the dotted lines going from the north to the south pole external to each magnet. The flux which enters the neck portion of the tube is of primary interest as this is the flux which controls the movement of the electron beams to achieve static convergence. The indicated flux lines of each of the magnets 27 intersect the ring 25b at common points indicated by theletters S and N. The letters S indicate the location of effective south magnetic poles and the letters N indicate the location of effective north magnetic poles. These effective magnetic poles haveessentially the same effect as if anactual magnet were placed in each of those locations, which magnet would have its south pole closest to the aperture corresponding to the neck region of the picture tube. It has been discovered that the arrangement in FIG. 4utilizing only two magnets 27 disposed as illustrated can perform the same function, i.e. movement of the two outer beams with substantially no movement of the inner beam, as the corresponding structure in the aforementioned Barbin application which utilizes four actual magnetic pole pairs, two of them having their north poles facing toward the neck region and two of them having their south poles facing toward the neck region. With the magnet ring arrangements as illustrated in FIG. 4, it can be seen that a substantial cost saving is achieved over the corresponding structure described in the Barbin application. A further advantage of the present arrangement is that with only two actual magnets used instead of four pole pairs there is a corresponding lesser possibility of magnetic strength variations in the magnets. It is desirable that all of the magnets of a given magnet ring member have substantially the same magnetic strength. The quadripolar magnetic field produced by ring member 25b permits, by rotation of ring member 25b relative to the picture tube, opposite direction movement of the two outside electron beams with substantially no effect on the inside one of the beams.

In FIG. 5 magnet ring member 24a contains three equal strength magnets 27 disposed at 120 intervals around the circumference of the ring 24a. Each of these magnets 27 has its south pole disposed closest to the neck region ofthe picture tube. As described for the ring member in FIG. 4, the magnetic flux lines of the magnets 27 effectively form additional magnetic poles midway between each two adjacent magnets in ring member 24a. Since the actual magnets have their south poles closest to the neck region north magnetic poles are effectively formed at the locations marked N and south magnetic poles at the locations marked S. Thus, in FIG. 5 the three magnets 27 effectively form a sextipolar magnetic field utilizing only half the number of actual magnetic pole pairs which are utilized in the corresponding structure in the aforementioned Barbin application. As in the arrangement of FIG. 4, advantages of this arrangement are a reduction of cost of the assembly and a lesser chance of magnet strength variations. The arrangement in FIG. 5 permits, by rotational movement of ring member 24a relative to the picture tube, the same direction movement of the two outside of the three in-line electron beams with substantially no effect on the center beam.

The ring member 250 is similar to ring member 25b illustrated in FIG. 4 with the exception that the magnets 27 are disposed such that the south poles are closest to the neck region, thus creating effective north magnetic poles half way between the south poles. Similarly, ring member 24b is similar to ring member 24a illustrated in FIG. 5 with the exception that the three magnets 27 are disposed such that their north poles are closest to the neck region thereby effectively forming three south magnetic poles equidistantly interspersed between the three north poles. Magnets 27 are retained in recesses formed in the faces of the ring members 24b and 24a. Another advantage of utilizing separate permanent magnets disposed at the desired intervals around the rings is that it is then easier to select magnets having the same field strength so that uniform motion of the two outside beams with substantially no effect on the center beam may be achieved. With a magnetizable ring such as the purtiy rings 22a and 22b, it becomes increasingly difficult to establish equal strength magnetic poles around the ring as the number of poles is increased. While it is desirable to have all of the magnets of an individual ring of equal strength, it may be necessary to vary the magnet strength from one ring to another to achieve convergence on different picture tube types.

FIGS. 6a, 6b and 6c illustrate the effect of the combined ring members 25a and 25b superimposed in the FIGURES for moving the outside electron beams in opposite directions, should this be necessary to achieve convergence of all three of the beams. In FIGS. 6a-6c, as well as in FIGS. 7a-7c and FIGS. -80, the latter two FIGURES to be described subsequently, only the magnetic poles of the actual magnets 27, which poles are closest to the neck region, are shown to avoid undue complication of the drawings. However, it should be understood that the hypothetical, or magnetic, poles effectively formed by the actual magnets are disposed as illustrated in the respective FIGS. 4 and 5.

In FIG. 4, the two ring members 25a and 25b are disposed such that the actual magnetic poles are from each other. With this configuration, the respective ring members aid each other to provide a maximum amount of movement in the opposite direction of the two outside beams. In this situation, the two beams are moved in opposite vertical directions. It is noted that the general direction of movement of the beams can be determined by application of the well-known principles of the right hand rule.

FIG. 6b illustrates the two ring members 25a and 25b having their respective magnetic poles superimposed. This superimposition, regardless of the angular displacement of the two rings together around the neck region, causes an effective cancellation of the magnetic field of each and thereby no movement of the beams is effected. Of course, to achieve this condition it should be understood that the relative strengths of all four of the magnets of the two ring members should be equal.

FIG. 6c illustrates the two ring members 25a and 25b disposed such that the diametric poles of one ring relative to the poles of the other ring are angularly disposed about 60 as illustrated. This arrangement still effects opposite direction motion of the two outside beams with substantially no effect on the center beam but the amount of movement is somewhat reduced relative to the fully aiding ring position of FIG. 6a.

FIGS. 7a-7c illustrate the effect of the two ring members 24a and 24b on movement of the two outside beams in substantially the same direction without affecting the center beam. FIG. 7a illustrates the magnetic poles of ring members 24a and 24b disposed about 30 from each other. This results in a relatively slight movement of the two outside beams in the direction indicated.

FIG. 7b illustrates the two ring members 24a and 24b angularly disposed relative to each other such that their respective magnetic poles are superimposed. This results in an effective cancellation of the magnetic field of each such that there is no movement imparted to the electron beams.

FIG. 7c illustrates the two ring members 24a and 24b angularly disposed such that their respective magnets are about 60 apart. Such an arrangement provides a maximum amount of movement of the two outside beams. This maximum amount of movement may be lar displacement of the two rings and rotating the two of them in unison around the neck of the tube.

FIGS. 8a-8c illustrate the efi'ect of the purity ring as sembly comprising purity rings 22a and 22b. These ring assemblies, as mentioned above, are of a conventional design and since each ring is diametrically magnetized with opposite polarity poles, there are no hypothetical magnetic poles effectivelyv formed as described .forring members 24a and b and ring members 25a and b. It will suffice to say that the purity rings provide the same direction movement of all three of the electron beams by rotation of the individual or both rings about the neck of the picture tube. This description of the conventional purity rings is included to illustrate how they may be used with the previously described ring members for providing a static convergence assembly which also enable purity adjustment.

In order to provide a static convergence and purity assembly which has minimum interaction with the field of the deflection yoke, it has been determined that one satisfactory order of placement of the rings along the neck of the picture tube from the neck region toward the deflection yoke is first the purity rings 22a and 22b, then the sextipolar field producing ring members 24a and 24b, and'finally the quadripolar magnetic beam producing ring members 25a and 25b.

Thus far in the description the static convergence assembly has incorporated two sets of ring members 24a and 24b, and 25a and 25b, both sets having magnets placed according to the invention. It should be understood that the invention may be practiced by utilizing one set of ring members according to the invention and the other set as described, for example, in the copending Barbin application. In such an arrangement the rings 25a and 25b may be as described in conjunction with FIG. 4, whereby only two actual magnets are required on each of the rings to produce the quadripolar fields. Ring members 24a and 24b would then each have six actual magnetic pole pairs or magnets instead of three. Of course, this arrangement may be reversed whereby rings 25a and 25b would each have four actual magnetic pole pairs ormagnets and each of rings 24a and 24b would hav e only three actual magnetic pole pairs or magnets, the latter rings being in accordance with the invention. l

FIG. 9 illustrates a magnet ring structure of the static convergence assembly in accordance with another embodiment of the invention and FIG. 10 is a cross sectional view of the magnet ring structure of FIG. 9. It should be noted that in the above-described embodiment of the invention two rings and their associated magnets wererequired to effect each of theopposite direction movement and common direction movement of the two outside electron beams. While the actual respective directions of movement could be accomplished with one each of the pairs of rings, the second respective rings having magnets of the opposite polarity from the first rings serves to control the amplitude or amount of movement in a given direction. Such an arrangement, of course, provides the full flexibility needed to satisfactorily converge the three beams.

In the embodiment illustrated in FIGS. 9 and 10, it is possible to control the same direction movement and opposite direction movement and the amount of that movement of the two outside beams with only one three-magnet magnet ring and one two-magnet magnet ring. Generally, this may be accomplished by any means which allows the strength of the magnetic field to be varied. This is accomplished in one manner in the embodiment of FIG. 9 which illustrates a two-magnet ring member which replaces the two magnet rings 25a and 25b of FIG. 2. Magnet ring 30 in FIG. 9 includes a plurality of tabs 31 to facilitate rotational movement about the neck of the tube. Magnet ring 30 includes recessed slots 32 extending from the inner to outer diameters of the ring 30 slots 32 extend within ring 30 beyond edge portions 33 of ring 30. Within these slots are disposed respective magnets 27 having like polarity poles pointed inwardy toward the neck aperture. Attached to magnets 27 by means of a suitable bonding agent such as epoxy are members 28 which extend outwardly farther than the outside diameter of the ring 30. The members 28 allow the magnets 27 to be adjusted radially within slots 32. With this arrangement the strength of the magnetic field may be varied 'in accordance with the radial distance of the magnets from the neck of the picture tube. Thus, rotational movement of the ring 30 with its magnets determines the direction of movement of the beams and adjustment of the radial position of the magnets 27 by means of the members 28 determines the amount of movement of the two outside beams in a given direction. The dimensions of the slots 32 are selected such that they'frictionally retain the magnets 27 once their positioning is adjusted.

The poles of the magnets 27 closest to the neck region of the picture tube both may be either north or south poles, which polarity will determine the polarity of the eifective poles formed therefrom by the magnetic flux. The theory of operation of the single ring 30 is the same as that described for ring member 25b of FIG. 4.

Similarly, a single ring may be substituted for the two three-magnet ring members 24a and 24b of FIG. 2 by providing three spaced slots 32 to receive three magnets 27 with their attached adjusting members 28. Again, the magnets 27 in the three-magnet embodiment may be selectedto have either their north or south poles closest toward the neck region as long as all three magnets are similarly disposed. The flux from the three magnets will effectively fonn three magnetic poles of the opposite polarity equidistantly spaced between adjacent ones of the three magnets. The magnet ring member 30 of FIG. 9 and 10 and its three magnet counterpart may also be made of a nonmagnetic material such as plastic and mounted on a similar structure including cylinder 17 as illustrated in FIG. 2.

What is claimed is:

l. A beam adjustment assembly for a multi-beam color cathode ray tube, comprising:

first and second permanent magnets;

a nonmagnetic supporting member having a central aperture for receiving the neck of said tube, said member supporting said first and second magnets on opposite sides of said aperture with like poles of said magnets directed toward said aperture for producing magnetic fields in opposite directions at dia-' metrically opposite sides of said aperture;

means positioned adjacent said nonmagnetic supporting member and having a central aperture therein for receiving the neck of said tube, said means providing a plurality of magnetic pole regions adjacent the central aperture thereof to produce magnetic fields in the same direction at diametrically opposite sides of said aperture; and means for adjustably supporting said member and said first-named means relative to one another.

2. A beam adjustment assembly for a multi-beam color cathode ray tube, comprising:

first, second and thrid permanent magnets;

a nonmagnetic supporting member having a central aperture for receiving the neck of said tube, said member supporting said first, second and third magnets at 120 intervals around the circumference of said aperture with like poles of said magnets directed toward said aperture for producing magnetic fields in the same direction at diametrically opposite sides of said aperture;

means positioned adjacent said nonmagnetic supporting member and having a central aperture therein for receiving the neck of said tube, said means providing a plurality of magnetic pole regions adjacent the central aperture thereof to produce magnetic fields in opposite directions at diametrically opposite sides of said aperture; and

means for adjustably supporting said member and said first-named means relative to one another.

3. A beam adjustment assembly for converging a plurality of spaced apart coplanar electron beams of a color cathode ray tube, comprising:

first means adapted to be adjustably rotatably mounted around the neck region of said tube, said first means including at least one set of a plurality of equally circumferentially spaced permanent magnets, all magnets of a set having like poles disposed toward the center of said neck region for producing opposite direction motion of substantially only the outside ones of said beams; and

second means adapted to be adjustably rotatably mounted around the neck region of said tube, said second means including at least one set of a plurali'ty of equally circumferentially spaced permanent magnets, all magnets of a set having like poles disposed toward the center of said neck region for producing the same direction motion of substantially only the outside ones of said beams.

4. A beam adjustment assembly according to claim 1 wherein said first means includes a second set of equally circumferentially spaced permanent magnets equal in number to said first set but having the opposite poles disposed toward said neck region; and

said second means includes a second set of equally circumferentially spaced permanent magnets equal in number to said first set but having the opposite poles disposed toward said neck region.

5. A beam adjustment assembly according to claim 3 wherein said set of magnets of said first means includes two permanent magnets adapted to be disposed adjacent diametrically opposite portions of said neck region, the magnetic flux paths of said two magnets effectively forming two poles of the opposite polarity of said first mentioned magnet poles diametrically opposite each other and disposed substantially equidistant circumferentially between said first mentioned two magnet poles; and

said set of magnets of said second means includes three permanent magnets adapted to be disposed at 120 intervals around the circumference of said neck region, the magnetic flux paths of said three magnets effectively forming three poles of the opposite polarity of said first magnet poles substantially equidistant circumferentially between said first mentioned three magnet poles.

6. A beam adjustment assembly according to claim 5 wherein said first means includes a set of magnets mounted adjacent to said first set and being similar to said first set except that the magnet poles are of opposite polarity; and

said second means includes a second set of magnets mounted adjacent to said first set and being similar to said first set except that the magnet poles are of opposite polarity. 7. A beam adjustment assembly according to claim 6 including third means adapted to be rotatably mounted around the neck region of said tube, said third means including two adjacent magnet rings each magnetized to have two opposite polarity magnetic poles diametrically across from each other.

8. A static convergence assembly for converging three in-line electron beams of a color television picture tube, comprising:

first means including a first member adapted to be mounted for rotation around the neck region of said picture tube, said member having first and second magnets disposed on diametric opposite sides thereof, said magnets being further disposed such that their magnetic poles of the same polarity are pointed radially inwardly toward said neck region for causing the two outside ones of said beams to move in opposite directions; and

second means including a second member adapted to be mounted for rotation around the neck region of said picture tube, said member having three magnets spaced at 120 intervals around said second member, said three magnets being further disposed such that their magnetic poles of the same polarity are pointed radially inwardly toward said neck region for causing the two outside ones of said beams to move in the same direction;

said first and second means being adapted to allow the varying of the intensity of the magnetic flux in said neck region.

9. A static convergence assembly in accordance with claim 8 wherein said first and second means are selected to permit radial movement of said magnets for varying the intensity of the magnetic flux in said neck region.

10. A static convergence assembly for converging three in-line beams of a color television picture tube comprising:

first and second adjacent members adapted for individual rotational movement about the neck region of said picture tube,

said first member including two diametrically opposed magnets having their north poles closest to the neck region, the flux from said magnets effectively forming two diametrically opposed magnetic south poles each located from said north poles,

said second member including two diametrically opposed magnets having their south poles closest to the neck region, the flux from said magnets effectively forming two diametrically opposed north poles each located 90 from said south poles, the quadripole fields of said first and second members cooperating to control the amount of movement in opposite directions of substantially only the twooutside ones of said beams;

and

third and fourth adjacent members disposed adjacent said first and second members adapted for individual rotational movement about the neck region of said picture tube,

.said third member including three magnets disposed at 120 intervals around the circumference of said neck region and having their north poles I closest to the neck region, the flux from said magnets effectively forming three 120 spaced south magnetic poles each spaced 60 from adjacent ones of said north poles,

said fourth member including three magnets disposed at 120 intervals around the circumference of said'neck region and having their south poles closest to the neck region, the flux from said magnets effectively forming three 120 spaced north magnetic poles each spaced 60 from adjacent one of said south poles,

the sextipolar fields of said third and fourth members cooperating to control the amount of movement in the same direction of substantially only the two outside ones of said beams.

11. A static convergence assembly for converging three in-line electron beams of a color television picture tube, comprising:

first means including a first member adapted to be mounted for rotation around the neck region of said picture tube, said member having first and second magnets disposed on diametric opposite sides thereof, said magnets being further disposed such that their magnetic poles of the same polarity are pointed radially inwardly toward said neck region for causing the two outside ones of said beams to move in opposite directions; and

second means including a second member adapted to be mounted for rotation around the neck region of said picture tube, said member having a plurality of magnets spaced equidistantly around said second member, said plurality of magnets producing magnetic fields for causing the two outside ones of said beams to move in the same directions;

said first and second means including means for allowing the varying of the intensity of the magnetic flux in said neck region.

12. A static convergence assembly for converging three in-line electron beams of a color television picture tube, comprising:

first means including a first member adapted to be mounted for rotation around the neck region of said picture tube, said member having a plurality of magnets spaced equidistantly around said member, said plurality of magnets producing magnetic fields for causing the two outside ones of said beams to move in opposite directions; and

second means including a second member adapted to be mounted for rotation around the neck region of said picture tube, said member having three magnets spaced at intervals around said second member, said three magnets being further disposed such that their magnetic poles of the same polarity are pointed radially inwardly toward said neck region for causing the two outside ones of said beams to move in the same direction;

said first and second means including means for allowing the varying of the intensity of the magnetic flux in said neck region.

Patent No- Dated 30,

Inventor(s) Ira Foy Thompson; Joseph Leland Smith It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the title sheet, the following should be inserted Foreign Application Priority Data March'ZO, 1972 Great Britain ..l2936/72 Column 3, line 56, "pruirty rings" should read purity rings Column 4, line 2, "rings 26" should read ring 26 line 38, "receiving forming should read receiving aperture for forming Column 5, line 59, "members 24b" should read members 25b Column 6, line 33, "This superimposition" should read This superposition Column 8, line 10, "ring 30 slots 32" should read ring 30.. Slots 32 line 13, "inwardy" should read inwardly Column 9, line 7, "thrid" should read third Signed and sealed this 29th day of October 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-1050 (10-69) USCOMM-DC scam-ps9 3530 6|72 v u.s4 GOVERNMENT PRINTING OFFICE: I969 o-ass-au UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 808 570 Dated April 30: 1974 Inventor(s) Ira Foy Thompson; Joseph Leland Smith It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the title sheet, the following should be inserted ForeignApplication Priority Data narch'zo, 1972 Great Britain... ..l2936/72 Column 3, line 56, "pruirty rings" should read purity rings Column 4, line 2, "rings 26" should read ring 26 line 38, "receiving forming" should read receiving aperture for forming Column 5, line 59, "members 24b" should read members 25b Column 6, line 33, "This superimposition" should read This superposition Column 8, line 10, "ring 30 slots 32" should read ring 30.. Slots 32 line '13, "inwardy" should read inwardly Column 9, line 7, "thrid" should read third I Signed and sealed this 29th day of October 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-1050 (10-69) I uscoMM-oc 60376-P69 fi U.S GOVERNMENT PRINTING DFFICE 1969 111-365-334 

1. A beam adjustment assembly for a multi-beam color cathode ray tube, comprising: first and second permanent magnets; a nonmagnetic supporting member having a central aperture for receiving the neck of said tube, said member supporting said first and second magnets on opposite sides of said aperture with like poles of said magnets directed toward said aperture for producing magnetic fields in opposite directions at diametrically opposite sides of said aperture; means positioned adjacent said nonmagnetic supporting member and having a central aperture therein for receiving the neck of said tube, said means providing a plurality of magnetic pole regions adjacent the central aperture thereof to produce magnetic fields in the same direction at diametrically opposite sides of said aperture; and means for adjustably supporting said member and said first-named means relative to one another.
 2. A beam adjustment assembly for a multi-beam color cathode ray tube, comprising: first, second and thrid permanent magnets; a nonmagnetic supporting member having a central aperture for receiving the neck of said tube, said member supporting said first, second and third magnets at 120* intervals around the circumference of said aperture with like poles of said magnets directed toward said aperture for producing magnetic fields in the same direction at diametrically opposite sides of said aperture; means positioned adjacent said nonmagnetic supporting member and having a central aperture therein for receiving the neck of said tube, said means providing a plurality of magnetic pole regions adjacent the central aperture thereof to produce magnetic fields in opposite directions at diametrically opposite sides of said aperture; and means for adjustably supporting said member and said first-named means relative to one another.
 3. A beam adjustment assembly for converging a plurality of spaced apart coplanar electron beams of a color cathode ray tube, comprising: first means adapted to be adjustably rotatably mounted around the neck region of said tube, said first means including at least one set of a plurality of equally circumferentially spaced permanent magnets, all magnets of a set having like poles disposed toward the center of said neck region for producing opposite direction motion of substantially only the outside ones of said beams; and second means adapted to be adjustably rotatably mounted around the neck region of said tube, said second means including at least one set of a plurality of equally circumferentially spaced permanent magnets, all magnets of a set having like poles disposed toward the center of said neck region for producing the same direction motion of substantially only the outside ones of said beams.
 4. A beam adjustment assembly according to claim 1 wherein said first means includes a second set of equally circumferentially spaced permanent magnets equal in number to said first set but having the opposite poles disposed toward said neck region; and said second means includes a second set of equally circumferentially spaced permanent magnets equal in number to said first set but having the opposite poles disposed toWard said neck region.
 5. A beam adjustment assembly according to claim 3 wherein said set of magnets of said first means includes two permanent magnets adapted to be disposed adjacent diametrically opposite portions of said neck region, the magnetic flux paths of said two magnets effectively forming two poles of the opposite polarity of said first mentioned magnet poles diametrically opposite each other and disposed substantially equidistant circumferentially between said first mentioned two magnet poles; and said set of magnets of said second means includes three permanent magnets adapted to be disposed at 120* intervals around the circumference of said neck region, the magnetic flux paths of said three magnets effectively forming three poles of the opposite polarity of said first magnet poles substantially equidistant circumferentially between said first mentioned three magnet poles.
 6. A beam adjustment assembly according to claim 5 wherein said first means includes a set of magnets mounted adjacent to said first set and being similar to said first set except that the magnet poles are of opposite polarity; and said second means includes a second set of magnets mounted adjacent to said first set and being similar to said first set except that the magnet poles are of opposite polarity.
 7. A beam adjustment assembly according to claim 6 including third means adapted to be rotatably mounted around the neck region of said tube, said third means including two adjacent magnet rings each magnetized to have two opposite polarity magnetic poles diametrically across from each other.
 8. A static convergence assembly for converging three in-line electron beams of a color television picture tube, comprising: first means including a first member adapted to be mounted for rotation around the neck region of said picture tube, said member having first and second magnets disposed on diametric opposite sides thereof, said magnets being further disposed such that their magnetic poles of the same polarity are pointed radially inwardly toward said neck region for causing the two outside ones of said beams to move in opposite directions; and second means including a second member adapted to be mounted for rotation around the neck region of said picture tube, said member having three magnets spaced at 120* intervals around said second member, said three magnets being further disposed such that their magnetic poles of the same polarity are pointed radially inwardly toward said neck region for causing the two outside ones of said beams to move in the same direction; said first and second means being adapted to allow the varying of the intensity of the magnetic flux in said neck region.
 9. A static convergence assembly in accordance with claim 8 wherein said first and second means are selected to permit radial movement of said magnets for varying the intensity of the magnetic flux in said neck region.
 10. A static convergence assembly for converging three in-line beams of a color television picture tube comprising: first and second adjacent members adapted for individual rotational movement about the neck region of said picture tube, said first member including two diametrically opposed magnets having their north poles closest to the neck region, the flux from said magnets effectively forming two diametrically opposed magnetic south poles each located 90* from said north poles, said second member including two diametrically opposed magnets having their south poles closest to the neck region, the flux from said magnets effectively forming two diametrically opposed north poles each located 90* from said south poles, the quadripole fields of said first and second members cooperating to control the amount of movement in opposite directions of substantially only the two outside ones of said beams; and third and fourth adjacent members disposed adjacent said first and second members adapted fOr individual rotational movement about the neck region of said picture tube, said third member including three magnets disposed at 120* intervals around the circumference of said neck region and having their north poles closest to the neck region, the flux from said magnets effectively forming three 120* spaced south magnetic poles each spaced 60* from adjacent ones of said north poles, said fourth member including three magnets disposed at 120* intervals around the circumference of said neck region and having their south poles closest to the neck region, the flux from said magnets effectively forming three 120* spaced north magnetic poles each spaced 60* from adjacent one of said south poles, the sextipolar fields of said third and fourth members cooperating to control the amount of movement in the same direction of substantially only the two outside ones of said beams.
 11. A static convergence assembly for converging three in-line electron beams of a color television picture tube, comprising: first means including a first member adapted to be mounted for rotation around the neck region of said picture tube, said member having first and second magnets disposed on diametric opposite sides thereof, said magnets being further disposed such that their magnetic poles of the same polarity are pointed radially inwardly toward said neck region for causing the two outside ones of said beams to move in opposite directions; and second means including a second member adapted to be mounted for rotation around the neck region of said picture tube, said member having a plurality of magnets spaced equidistantly around said second member, said plurality of magnets producing magnetic fields for causing the two outside ones of said beams to move in the same directions; said first and second means including means for allowing the varying of the intensity of the magnetic flux in said neck region.
 12. A static convergence assembly for converging three in-line electron beams of a color television picture tube, comprising: first means including a first member adapted to be mounted for rotation around the neck region of said picture tube, said member having a plurality of magnets spaced equidistantly around said member, said plurality of magnets producing magnetic fields for causing the two outside ones of said beams to move in opposite directions; and second means including a second member adapted to be mounted for rotation around the neck region of said picture tube, said member having three magnets spaced at 120* intervals around said second member, said three magnets being further disposed such that their magnetic poles of the same polarity are pointed radially inwardly toward said neck region for causing the two outside ones of said beams to move in the same direction; said first and second means including means for allowing the varying of the intensity of the magnetic flux in said neck region. 